1. Field of the Invention
The present invention relates to an electronic device, and more particularly to an electronic device, such as a scientific electronic calculator having a verification function.
2. Description of Related Art
Electronic devices, such as scientific electronic calculators, having a verification function have been known. For example, Japanese Unexamined Patent Application Publication No. 2000-298423 discloses a calculation display device. When a user inputs an arithmetic expression, inputs a solution obtained by the user's own calculation, and performs a key operation for verification of the solution, the calculation display device disclosed in this document compares the user's solution with a plurality of solutions of the arithmetic expression and displays the information representing “true” or “false” (i.e., “correct” or “incorrect” etc.).
Japanese Unexamined Patent Application Publication No. 2011-232468 discloses an electronic device having a verification function to determine whether the solution of an input equation matches the solution of an input deformed equation. The electronic device disclosed in this document can perform a verification process when a replacement equation is input, which replacement equation is an equation with a replacement expression input by a user.
With a scientific electronic calculator hitherto known having a verification function, when an expression including an equality sign (=) or an inequality sign (>, <, ≥, ≤) is input, the calculator compares the left side member with the right side member and determines whether the equality or inequality is true, i.e., determines the truth or falseness.
When a user develops an expression on a sheet of paper, such as a notebook, he or she usually develops the expression step by step by writing the following expressions.
                                                                                          (                                      x                    +                    1                                    )                                ⁢                                  (                                      x                    +                    5                                    )                                            =                            ⁢                                                x                  2                                +                x                +                                  5                  ⁢                  x                                +                5                                                                                        =                            ⁢                                                x                  2                                +                                  6                  ⁢                  x                                +                                  5                  ⁢                                      (                    2                    )                                                                                                          (        1        )            
When the developed expression is to be verified with the verification function of an electronic device hitherto known, the expression (x+1) (x+5)=x2+x+5x+5 . . . (1) is input and the truth or falseness is determined by the verification function. If the expression is determined to be true, a user has to newly input the right side member of the mathematical expression (1) as the left side member, in such a manner as “x2+x+5x+5=x2+6x+5”, to input an expression to be determined next.
Similar problems arise in the case of factorizations and mathematical expressions with inequality signs etc. Hence, better usability has been demanded for electronic devices with a verification function.